Sensor device for measuring a quantity characterizing the rotational state of a shaft part of a motor vehicle and method for manufacturing a sensor part.

Abstract

Sensor device for measuring a quantity characterizing a rotational state of a shaft part of a motor vehicle, in particular a steering shaft of the motor vehicle, comprising a base body (11) that can be connected to the shaft part of the motor vehicle, and a magnetic ring element (17, 18) arranged on the base body (11) for guiding magnetic flux from a magnet (6) to a flux conductor (7), wherein at least one recess (28, 29) for a corresponding fastening element (27) of the base body (11) is formed in the magnetic ring element (17, 18) and the magnetic ring element (17, 18) has a radially extending, annular base part (19, 20) from which the magnetic flux can be transmitted to the flux conductor (7), wherein the at least one recess (28, 29) extends radially to an inner edge (23, 24) of the annular base part (19, 20) 20) closer than an outer edge (32) of the base part (19,20) is arranged, characterized in that the magnetic ring element (17, 18) has at least one tab (30) projecting radially inwards from the annular base part (19, 20), in which the recess (28, 29) is formed.

Description

[0001] The invention relates to a sensor device for measuring a quantity characterizing the rotational state of a shaft component of a motor vehicle – in particular a steering shaft of the motor vehicle – such as torque and / or steering angle. The sensor device comprises a base body that can be connected to the shaft component of the motor vehicle. The sensor device also comprises a magnetic ring element – ​​in particular made of a soft magnetic material – which is arranged non-rotatably on the base body and is designed to conduct magnetic flux from a magnet to a flux conductor. The magnetic ring element has at least one recess for a corresponding fastening element of the base body, and the magnetic ring element has a radially extending, annular base part from which the magnetic flux can be transmitted to the flux conductor.The invention also relates to a method for providing a sensor part of a sensor device.

[0002] The present case focuses in particular on a sensor device by which the steering angle—and consequently the torque—of a motor vehicle's steering shaft can be measured. Such sensor devices are already state of the art and are generally used in electric steering systems. For example, German patent application DE 102 40 049 A1 describes such a sensor arrangement, which is designed to detect the torque acting on a motor vehicle's steering shaft. The sensor device is mounted on two axially opposed sections of the steering shaft. A magnet—namely, a ring magnet—is located on the first section, while a magnetic field sensor is mounted on the other section, positioned radially opposite the permanent magnet across a gap or air gap.

[0003] Such a sensor device typically consists of two units or sensor components: a ring magnet on the one hand and a magnetic sensor on the other, which serves to detect the magnetic field of the permanent magnet. While the permanent magnet is attached to a first shaft section of the steering system, the magnetic sensor is usually arranged on a second shaft section, which is connected to the first shaft section via a torsion bar. The sensor device detects the relative movement of the first shaft section with respect to the second shaft section.

[0004] A sensor device of the aforementioned type is also known from publication DE 10 2007 043 502 A1. This document describes a flux guide element which serves to guide the magnetic flux from a magnetic ring element (stator) to a Hall sensor.

[0005] Furthermore, the following state of the art is known: Document KR 10 2011 0 038 280 A describes a torque sensor and its manufacturing process. The invention aims to improve the precision and performance of the sensor by ensuring a stable and accurate positional relationship between the rotor body and the upper and lower stators. This is achieved by uniformly securing the magnetic absorption surfaces to the inner surface of the rotor body. The manufacturing process includes injection molding the rotor body and subsequent hot-melt joining of the stators to prevent their displacement or deformation.

[0006] Document US 2005 / 0247138 A1 describes a torque sensor for measuring shaft torque. It addresses the challenge of precisely positioning and fixing magnetic yokes within the sensor. The invention uses a non-magnetic spacer between the magnetic yokes, with both components integrated by resin molding. This design ensures accurate axial and circumferential positioning of the magnetic yokes, thus improving the precision and performance of the sensor.

[0007] The invention relates in particular to a sensor device as described in document WO 2009 / 035266 A2. As already explained, such a sensor device typically consists of two sensor parts that can be rotated relative to each other, namely the ring magnet on the one hand and the magnetic sensor for detecting the magnetic field on the other. The magnetic sensor in turn includes – as described in particular in the Fig. 2 and Fig. Figure 3 of the aforementioned publication depicts a base body or holder made of plastic and a stator fixed to the base body. This stator consists of two magnetic ring elements or stator parts, each with a multitude of axially extending magnetic teeth projecting from a radially extending, ring-shaped base. The two magnetic ring elements together form the stator and serve to receive the magnetic flux of the ring magnet and to transmit the magnetic flux to the aforementioned flux conductor and from there to the Hall sensor. The stator and the ring magnet are each rigidly attached to the partial shafts connected by a torsion bar and can therefore rotate together with the shaft.A moment applied to the shaft twists the torsion bar slightly, resulting in a small relative rotation between the stator and the ring magnet.

[0008] The device described in document WO 2009 / 035266 A2 features a multitude of recesses, each in the form of a through-hole, in the magnetic ring element. These recesses are located on the radial, annular base of the magnetic ring element. Corresponding pins or bolts of the base body can be inserted into these recesses to attach the magnetic ring element to the base body. A disadvantage of this device is that these recesses or pins significantly impair the transmission of magnetic flux from the magnetic ring element to the aforementioned flux conductor and then to the Hall sensor. The flux conductor must be positioned as close as possible to the axial end face or end surface of the annular base of the ring element to ensure reliable magnetic flux transmission.However, this is not possible due to the fastening elements. This problem will now be addressed with reference to the existing [documents / documents]. Fig. 1 and Fig. 2 explained in more detail: In the Fig. 1 and Fig. Figure 2 shows a stator 1 consisting of two magnetic ring elements 2, 3. Each ring element 2, 3 has a ring-shaped base 4 extending radially and forming a radial flange. The ring elements 2, 3 each have a plurality of axially extending teeth 5, arranged circumferentially and projecting axially from the respective base 4. A ring magnet 6 is arranged in a radial interior space of the stator 1, positioned a short distance from the teeth 5, creating an air gap between the ring magnet 6 and the stator 1. The ring magnet 6 is mounted on a first shaft section of the vehicle steering system, while the stator 1 is mounted on a second shaft section of the steering system, which is connected to the first shaft section via a torsion bar.When the two shaft sections are rotated relative to each other, the stator 1 also rotates relative to the ring magnet 6, and the teeth 5 become magnetically charged with opposite polarities. The resulting magnetic flux is then picked up by a flux conductor 7 and transmitted to a Hall sensor. The flux conductor 7 is positioned at a small distance from the two magnetic ring elements 2. The flux conductor 7 does not move with the stator 1. This means that when the stator 1 moves relative to the ring magnet 6, the flux conductor 7 remains stationary. In other words, there is relative movement between the stator 1 and the flux conductor 7. Furthermore, the steering shaft with the stator and ring magnet rotates around the common axis. The flux conductor 7 must not, in principle, interfere with the stator 1.The two ring elements 2 must not touch; on the other hand, the axial distance between the flux conductor 7 and the stator 1 should be as small as possible to ensure the transmission of the magnetic flux. This is only conditionally possible with the stator according to publication WO 2009 / 035266 A2 due to the through-holes in the stator and the corresponding pins.

[0009] In the Fig. 1 and Fig. Figure 2 shows two different types of flow conductor 7. Fig. 1. A U-shaped flow conductor 7 is used, which surrounds the two ring elements on both sides. In contrast, in Fig. 2. A flow conductor 7 is used, which is arranged exclusively between the two ring elements 2. It is also conceivable that appropriately shaped flow conductors are only located opposite the outer sides of the ring elements. In any case, a minimal distance is important for optimal function. It becomes apparent that the in the Fig. 1 and Fig. The functions of the two flow conductors 7 shown would be impaired if the stator were used in accordance with document WO 2009 / 035266 A2.

[0010] The object of the invention is to demonstrate a way in which, in a sensor device of the aforementioned type, on the one hand a simple and reliable attachment of the magnetic ring element to the base body and, on the other hand, the proper functioning of the sensor device can be enabled.

[0011] This problem is solved according to the invention by a sensor device and by a method with the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description, and the figures.

[0012] A sensor device according to the invention is designed to measure a quantity characterizing the rotational state of a shaft component of a motor vehicle – in particular, the rotational state of a shaft component of a steering shaft. This quantity is preferably a torque and / or a steering angle. The sensor device comprises a base body and a magnetic ring element arranged on the base body. The ring element is preferably made of a soft magnetic material. The base body can be connected to the shaft component of the motor vehicle. The magnetic ring element serves to conduct magnetic flux from a magnet (e.g., ring magnets) to a flux conductor. The magnetic ring element has at least one recess for a corresponding fastening element – ​​e.g., a bolt or screw.The magnetic ring element has a radially extending, annular base part from which the magnetic flux can be transferred to the flux conductor. According to the invention, the at least one recess is arranged radially closer to an inner edge of the annular base part than to an outer edge of the base part.

[0013] Unlike in document WO 2009 / 035266 A2 – where the recess is located in the radial center of the annular base part – the recess in the sensor device according to the invention is located closer to the inner edge of the base part, i.e., shifted radially inwards compared to the prior art. This ensures, on the one hand, that the magnetic ring element can be easily attached to the base body, because the recess can be retained, and on the other hand, that the proper functioning of the sensor device is guaranteed. The flux conductor can be arranged at a minimal distance from the axial end face of the annular base part without impairing the transmission of the magnetic flux through the fastening element – ​​for example, a rivet head. In the sensor device according to the invention, sufficient space is available for the flux conductor in the radial direction.

[0014] While at least one recess can be formed entirely within the annular base of the magnetic ring element, for example in an edge region or in the region of the inner edge of the base, it proves particularly advantageous if, according to the invention, the magnetic ring element has at least one tab projecting radially inwards from the annular base in which the recess is formed – at least partially. This leaves a larger end face of the base available for the flux conductor, so that the base does not need to be enlarged in the radial direction.

[0015] For example, the recess can be formed partially in the radial tab and partially in the annular base part. In this embodiment, the recess can be arranged, for instance, along a circular path defined by the inner edge of the base part. Thus, the tab can be designed to be space-saving in the radial direction towards the inside.

[0016] Alternatively, the entire recess can be formed within the radial tab. In this case, the recess is entirely located within the tab projecting radially from the base part. This ensures that the entire end face of the base part is free of any fasteners and thus fully available for the flow guide.

[0017] To achieve a particularly stable and reliable attachment of the magnetic ring element to the base body, the recess can be an axial through-hole in the magnetic ring element. Such a through-hole can be a punched hole or a through-bore. This embodiment ensures, in particular, a radially play-free attachment of the ring element to the base body.

[0018] When installation space is limited in the radial direction inwards, the recess can also be formed only partially, i.e., open inwards. This means that the recess can be designed to be open inwards in the radial direction, essentially forming a radial bay. This design is particularly space-saving and still allows for a reliable and slip-resistant attachment of the magnetic ring element to the base body.

[0019] As already explained, at least one axial end face – in particular both end faces – of the annular base part can be free of fastening elements. Then the entire axial end face of the base part is available for the flux conductor or for the transmission of the magnetic flux.

[0020] The magnetic element can have a multitude of magnetic teeth projecting axially from the annular base part – particularly from its radial inner edge – and arranged circumferentially, which are designed to receive the magnetic flux of the magnet. These magnetic teeth thus form quasi pole shoes, which capture the magnetic field from the magnet and transmit the magnetic flux to the annular base part and thereby to the flux conductor and the Hall sensor.

[0021] Preferably, at least one recess is arranged in the circumferential direction between two adjacent teeth, so that the magnetic flux is not negatively affected by the recess or the fastening element.

[0022] A method according to the invention is designed for manufacturing a sensor component of a sensor device by which a quantity characterizing the rotational state of a shaft component of a motor vehicle, in particular a steering shaft, is measured. A magnetic ring element for guiding magnetic flux and a base body with at least one fastening element are provided, wherein the magnetic ring element is formed with a radially extending, annular base part. A recess for the corresponding fastening element is provided in the magnetic ring element. The magnetic ring element is attached to the base body by inserting the fastening element into the recess. The recess is formed radially closer to an inner edge of the annular base part than to an outer edge of the base part.

[0023] After inserting the bolt-shaped fastener into the recess, one free end of the fastener can be formed into a rivet head. This allows the magnetic ring element to be held particularly reliably to the base body. Forming the fastener into a rivet head is an easy-to-control process that can be inspected both in terms of its force-displacement characteristics and visually for quality. Forming can be carried out, for example, by hot forming or by ultrasound.

[0024] The preferred embodiments and their advantages presented with reference to the sensor device according to the invention apply accordingly to the method according to the invention.

[0025] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. All features and combinations of features mentioned above in the description, as well as those subsequently mentioned in the description of the figures and / or shown in the figures alone, are usable not only in the combinations specified, but also in other combinations or individually.

[0026] The invention will now be explained in more detail with reference to a preferred embodiment and the accompanying drawings.

[0027] They show: Fig. 1 and Fig. 2 in schematic representation each a stator and a ring magnet of a sensor device according to the prior art; Fig. 3 in schematic representation a sensor part of a sensor device according to an embodiment of the invention; Fig. 4 in schematic representation a section of a magnetic ring element of the sensor device; and Fig. 5 in schematic representation the sensor part from a back side.

[0028] In Fig. Figure 3 shows a sensor element 10 of a sensor device designed to measure the torque and / or steering angle of a steering shaft of a motor vehicle. The steering shaft comprises two shaft sections connected to each other by a torsion bar. The sensor element 10 is rotationally fixed to one of the shaft sections via a base body 11, while a ring magnet 6 (in Fig. 3 not shown, see the Fig. 1 and Fig. 2) is held in a rotationally fixed position. The base body 11 serves as a holder for a stator 12. The base body 11 can be a single-piece plastic part. Optionally, the base body 11 can also be provided with a metal sleeve or other fastening elements such as tabs, hooks, clips, and the like, to attach the base body 11 to the associated shaft section. The base body 11 has a cylindrical mounting area 13 by means of which the base body 11 can be attached to the associated shaft section.

[0029] The base body 11 also has a cylindrical connection area 14, which has a slightly larger diameter than the mounting area 13. The connection area 14 is connected to the mounting area 13 via a plurality of circumferentially distributed pairs of legs 15. The connection area 14 is arranged concentrically with respect to the mounting area 13.

[0030] Between the pairs of legs 15, recesses or windows 16 are formed in the circumferential direction.

[0031] Two magnetic ring elements 17, 18 of the stator 12, which are made, for example, of a soft magnetic material, are arranged at the connection area 14. The magnetic ring elements 17, 18 are attached to the connection area 14. They each have a radially extending annular or circular and plate-like base part 19 or 20, respectively. A first ring element 17 is arranged on an end face of the connection area 14 of the base body 11 facing away from the mounting area 13, while the other ring element 18 is arranged on an end face of the connection area 14 facing the mounting area 13.

[0032] The ring elements 17, 18 each have a plurality of magnetic teeth 21 and 22, respectively, which project axially from the respective radial base part 19, 20, towards the other ring element 17, 18. The magnetic teeth 21, 22 thus point towards the other ring element 17 and 18. The teeth 21 of the first ring element 17 project into spaces formed between the teeth 22 of the second ring element 18, so that the teeth 21 and teeth 22 are arranged alternately in the circumferential direction. This means that a tooth 21 of the first ring element 17 lies between two adjacent teeth 22 of the second ring element 18. All teeth 21, 22 can bear against an inner circumference of the connection area 14 of the base body 11. However, this is not necessary, so alternatively the centering can also be done exclusively via the fastening elements 27 and recesses 28, 29 mentioned below.

[0033] The respective teeth 21 and 22 protrude from a radial inner edge 23 and 24 of the respective base part 19 and 20.

[0034] As previously explained, a plurality of windows 16 are formed between the connection area 14 and the mounting area 13 of the base body 11, located between the pairs of legs 15. These windows 16 form entry openings for the teeth 22 of the second ring element 18. This ring element 18 is attached to the base body 11 from the rear side via the mounting area 13. The teeth 22 of the ring element 18 can then be inserted into the respective corresponding windows 16 and thereby brought into contact with the inner circumference of the connection area 14. Similarly, the teeth 21 of the first ring element 17 are inserted into this cylindrical connection area 14 from the end face of the connection area 14 facing away from the mounting area 13, in order to be brought into contact with the inner circumference of the connection area 14.Corresponding pockets 25, 26 are formed on the inner circumference of the connection area 14, which serve as axial guides for the respective teeth 21, 22. The pockets 25, 26 are formed as recesses in the inner circumference of the connection area 14.

[0035] To fasten the two ring elements 17, 18 to the connection area 14, a plurality of circumferentially distributed fastening elements 27 are provided on each of the two axial end faces of the connection area 14 of the base body 11, projecting axially from the respective end face of the connection area 14. The fastening elements 27 are designed here as pins or bolts, which are connected by corresponding recesses 28 and 29, respectively (see also Fig. 5) extend through the respective base part 19 or 20 and their free ends are formed into rivet heads.

[0036] As from Fig. As shown in Figure 4, which depicts a section of a magnetic ring element 17, 18 in more detail, the recesses 28, 29 are provided in the form of through-openings or through-bores, which are formed in respective tabs 30. The tabs 30 project radially from the annular base part 19, 20 and point radially inwards. The recesses 28, 29 can be formed either completely in the respective tab 30 or partially in the base part 19, 20. Optionally, the tabs 30 can be omitted, and the recesses 28, 29 can be formed completely in the base part 19, 20. The essential point is that the recesses 28, 29 are arranged in the region of the inner edge 23, 24 of the base part 19, 20 and thus form an axial end face.The end face 31 of the base part 19, 20 is at least predominantly exposed, so that the axial end face 31 is at a very small axial distance to a flow conductor (as in the . Fig. 1 and Fig. (as shown in Figure 2). The recesses 28, 29 are therefore located closer to the inner radial edge 23, 24 of the base part 19, 20 than to an outer radial edge 32. This is especially true if the recesses 28, 29 are formed in the tabs 30, i.e., beyond the inner edge 23, 24.

[0037] The recesses 28, 29 are also arranged circumferentially between each pair of adjacent teeth 21 and 22, respectively. The transmission of the magnetic flux is therefore not impaired.

[0038] In Fig. Figure 5 shows the sensor part 10 from its rear side. The second magnetic ring element 18 and the cylindrical mounting area 13 are particularly visible here. As shown in Figure 5, the sensor part 10 is shown from its rear side. Fig. As shown in Figure 5, an axial guide 33 is formed between the legs of each pair of legs 15, in which the associated tab 30 of the ring element 18 is guided when it is placed onto the base body 11. The legs 15 engage in corresponding radial recesses 34 formed in the base part 20 of the ring element 18. This simplifies the alignment of the ring element 18 when it is placed onto the base body 11.

[0039] The pockets 25, 26 formed on the inner circumference of the connection area 14 of the base body 11 for the teeth 21, 22 also serve as alignment aids. They are designed to be slightly wider than necessary to prevent dimensional inaccuracies. Nevertheless, these pockets 25, 26 serve as alignment aids during the axial insertion of the respective ring element 17 or 18 during assembly, thus facilitating the insertion of the fastening elements 27 into the corresponding recesses 28 or 29.

[0040] During the production of the in the Fig. 3 and Fig. In the sensor part 10 shown in Figure 5, the base body 11 made of plastic and the two ring elements 17, 18 made of soft magnetic material are first provided. The base body 11 is formed with the fastening elements 27 in the form of pins or bolts, and the recesses 28, 29 are formed in the tabs 30 or (if no tabs 30 are used) in the area of ​​the inner edge 23, 24. The two ring elements 17, 18 are brought into contact with the respective end faces of the connection area 14 so that the magnetic teeth 21, 22 are inserted into the cylindrical space bounded by the connection area 14, specifically into the respective pockets 25, 26. The teeth 22 of the second ring element 18 are thereby inserted through the windows 16 into the interior.The fasteners 27 then enter the corresponding recesses 28, 29, so that the free ends of the fasteners 27 protrude from the recesses 28, 29 on the other side. These free ends are then formed into rivet heads, either by hot forming or by ultrasonic forming.

[0041] A ring magnet 6 (as in the Fig. 1 and Fig. 2 shown) is introduced, which is arranged on the other shaft part of the vehicle steering system. This ring magnet 6 is then located at a radial distance from the teeth 21, 22. For the ring elements 17, 18 according to the Fig. 3 and Fig. In principle, any flow conductor 7 can be used. For example, the flow conductor according to Fig. 2 can be used, which extends in the axial direction between the two ring elements 17, 18. However, the flow conductor 7 can also be used according to Fig. 1 is used, which partially encloses the respective base parts 19, 20 of the ring elements 17, 18. The fastening elements 27 and the recesses 28, 29 do not preclude this.

Claims

[1] Sensor device for measuring a quantity characterizing a rotational state of a shaft part of a motor vehicle, in particular a steering shaft of the motor vehicle, comprising a base body (11) that can be connected to the shaft part of the motor vehicle, and a magnetic ring element (17, 18) arranged on the base body (11) for guiding magnetic flux from a magnet (6) to a flux conductor (7), wherein at least one recess (28, 29) for a corresponding fastening element (27) of the base body (11) is formed in the magnetic ring element (17, 18) and the magnetic ring element (17, 18) has a radially extending, annular base part (19, 20) from which the magnetic flux can be transmitted to the flux conductor (7), wherein the at least one recess (28, 29) extends radially to an inner edge (23, 24) of the annular base part (19, 20) closer than an outer edge (32) of the base part (19,20) is ordered, , characterized by , that the magnetic ring element (17, 18) has at least one tab (30) projecting radially inwards from the ring-shaped base part (19, 20), in which the recess (28, 29) is formed. [2] Sensor device according to claim 1, characterized by , that the recess (28, 29) is formed in the radial tab (30) in some areas and in the annular base part (19, 20) in some areas. [3] Sensor device according to claim 1, characterized by , that the entire recess (28, 29) is formed in the radial tab (30). [4] Sensor device according to one of the preceding claims, characterized by , that the recess (28, 29) is an axial through-opening in the magnetic ring element (17, 18). [5] Sensor device according to any one of claims 1 to 3, characterized by , that the recess (28, 29) is open in a radial direction towards the inside. [6] Sensor device according to one of the preceding claims, characterized by , that the magnetic ring element (17, 18) has a plurality of magnetic teeth (21, 22) projecting axially from the annular base part (19, 20) and arranged circumferentially, which are designed to receive the magnetic flux of the magnet (6). [7] Sensor device according to claim 6, characterized by , that at least one recess (28, 29) is arranged in the circumferential direction between two adjacent teeth (21, 22). [8] Method for manufacturing a sensor part (10) of a sensor device by which a quantity characterizing a rotational state of a shaft part of a motor vehicle, in particular a steering shaft of the motor vehicle, is measured, comprising the steps: - Providing a magnetic ring element (17, 18) for conducting magnetic flux and a base body (11) with at least one fastening element (27), wherein the magnetic ring element (17, 18) is formed with a radially extending, annular base part (19, 20), - Providing a recess (28, 29) in the magnetic ring element (17, 18) for the corresponding fastening element (27) and - Attaching the magnetic ring element (17, 18) to the base body (11) by receiving the fastening element (27) in the recess (28, 29), wherein the recess (28, 29) is formed in a radial direction closer to an inner edge (23, 24) of the annular base part (19, 20) than to an outer edge (32) of the base part (19, 20), characterized by, that the magnetic ring element (17, 18) is formed with at least one tab (30) projecting radially inwards from the ring-shaped base part (19, 20), in which the recess (28, 29) is formed. [9] Method according to claim 8, characterized by , that after the bolt-shaped fastening element (27) is inserted into the recess (28, 29) a free end of the fastening element (27) is formed into a rivet head.

Images